Figure 1. Biased Diffusion exhibited by MT1-MMP on The Surface of Collagen Fibrils is absent in a catalytically inactive mutant E240->A.

(A). SDS-PAGE analysis of Gel filtration Chromatography of the MT1-MMP expressed in E.Coli: MW standards (lane 1); the leading portion of the major protein peak (lane 2); trailing portion of the major protein peak (lane 3); activation of the MT1-MMP (lane 3) with recombinant Furin for 30 min at 300C (lane 4). (B). Normalized experimental correlation functions obtained from collagen fibrils decorated with either activated MT1-MMP Wild Type (open circles) or MT1-MMP inactive mutant (E240->A, closed circles) were calculated from the 400 µs binned data records as described in Methods. The background was suppressed using the spatial background filter described earlier [13], see methods). Three experimental correlation functions for each enzyme were normalized and then averaged to obtain the data shown. The experimental correlation function for wild-type enzyme was fitted (Methods, equation 3) to a 1D diffusion (D = 6.0±0.05×10⁻⁹ cm² s⁻¹) plus flow (V = 5.8±0.2 µm s⁻¹) model. The correlation function of the inactive mutant exhibits a long tail characteristic of an unbiased 1-D diffusion, accordingly, a fit of the same equation (Methods, equation 3) yielded a local diffusion coefficient (D = 1.1±0.04×10⁻⁸ cm² s⁻¹) and no significant flow.